He also suffered some bumps and bruises in the first period, responding with a nasty challenge on Claudio Yacob, becoming briefly fractious and increasingly barracked by the home fans. This was proving a test of character.
Wilshere was also clearly not relishing his role on the left. It would have been little surprise if he had been replaced by Tomas Rosicky at the interval.
Yet Wilshere responded well to the half-time words of Wenger and delivered a strong performance in the second half, capped by that goal, which still required a deflection off Jonas Olsson.
For all the critical focus on Wilshere, he reports to St George's Park on Monday evening as an important figure for England in their pursuit of six points against Montenegro and Poland that will guarantee qualification for the World Cup finals.
Wilshere's second-half contribution highlighted the sort of touch, work-rate and defiance that England will need.
Arsenal, too. This is proving an unpredictable season; few would have anticipated a top-four of Arsenal, Liverpool, Chelsea and Southampton going into the October international break. Few would have tipped such results as West Bromwich's win at Manchester United last week.
Steve Clarke's side certainly deserved this point. Boaz Myhill was excellent in goal, making one particularly athletic save from Olivier Giroud.
Clarke has his defence so well organised while the wholehearted Billy Jones also raided down the right. Yacob took his first goal for the club well, a fine 42nd-minute header. Alongside Yacob in deep midfield, Youssouf Mulumbu was superb, constantly disrupting Arsenal moves. Both were equal contenders for man of the match.
Out on the left, Saido Berahino highlighted his promise with some skilful moments on his first Premier League start. One touch to drag the ball away from the vaunted Mesut Özil demonstrated the technique and fearlessness of the 20-year-old. West Bromwich were unfortunate that Nicolas Anelka's was off-form against his old club.
Such was the quality of West Bromwich's defending that Özil had to move wide or drop deep on occasion. It was a day for Arsenal celebrating left-footed creativity, being the 40th anniversary of Liam Brady's debut for the club (against Birmingham City), but Özil had no joy for an hour as Arsenal laboured to find a path through.
Özil, showing his two-footed passing range, was still influential, outjumping Gareth McAuley, and often linking with Aaron Ramsey but West Brom's striped wall stood firm. Mikel Arteta did make space but his shot hit Giroud. The Frenchman was then stopped by Yacob with a tackle that the Pumas would have admired. Özil placed the ball down, stole a yard but it was Ramsey who took the free-kick, thumping it over.
Arsenal had more possession but West Bromwich occasionally threatened even before Yacob's goal. Berahino's shot clipped Mathieu Flamini, forcing Wojciech Szczesny to dive to his right, stretch out a hand and push the ball away.
The game briefly became scrappy. Flamini collected his seemingly obligatory booking for catching Morgan Amalfitano. Wilshere took an accidental whack in the face from Yacob. He did not look in the mood to turn the other cheek.
West Bromwich were certainly not in awe of visitors who had started the season so strongly. Their fans bayed for a free-kick when Stephane Sessegnon was clearly pushed over by Kieran Gibbs just outside the box but Lee Mason waved play on. West Bromwich fans booed Wilshere for either staying down or showing dissent. They then cheered when Myhill dealt with Ramsey's long, low strike.
Three minutes from the break, Yacob then made the most decisive intervention of the first half. Mulumbu swept a clearance right to Amalfitano, whose cross rose perfectly for Yacob, who headed past Szczesny.
Wenger stood in the dug-out, looking on in frustration. West Bromwich fans laughingly reminded him of their club's reputation for ending the reigns of opposing managers like Paolo Di Canio. "We're the Albion, we'll sack who we want,'' the home fans chorused.
Wilshere continued to have a distracted afternoon until that 64th-minute strike. He leapt in on Yacob, who was fortunate to escape without injury. Wilshere calmed down at the break but Arsenal were still spluttering. Berahino went on one dazzling run, taking him past Per Mertesacker, and crossing to the far-post where Anelka failed to appreciate the gift of a ball.
Giroud then sent Wilshere into the box but he shot over when forcefully challenged by Jones. Still West Bromwich should have scored when Anelka, running on to Liam Ridgewell's pass down the left, curled his shot wide of Szczesny's left-hand upright.
Wenger made a change, withdrawing Ramsey for Tomas Rosicky, who was involved in Arsenal's 64th-minute leveller. Özil began the move on the right, picking out Giroud. Rosicky laid the ball back to Wilshere, who met it first time from 25 yards. Myhill appeared to have it covered but it clipped Olsson and flew in.
Clarke's men refused to be cowed. Shane Long replaced Anelka and proved highly effective. This was now a superb game, moves fizzing from end to end, chances coming and going. Jones's drive was saved by Szczesny. Myhill did brilliantly to claw Giroud's shot away. Berahino, hardly lacking in confidence, dragged the ball away from Özil.
Wilshere looked bemused when Mason waved play on after he fell under Mulumbu's challenge in the box.
West Brom themselves deserved a penalty in added time when Laurent Koscielny bumped into Long but Mason ignored the offence.
At the final whistle, Wilshere strolled over to thank the Arsenal fans for their support, throwing his sweat-stained shirt over the hoardings.