Paul Cook's Chesterfield were good value for a first-half lead, courtesy of Jay O'Shea, only for Kortney Hause to level matters in first-half stoppage time.
Both sides went close after the interval but Jo Kuffour's brilliantly improvised finish - his first goal in Wycombe colours - consigned the visitors to a third successive league defeat on their travels.
Ainsworth said: "For 44 minutes we didn't turn up and I've told the lads, it's the second time I've had to lose it with them.
"That has been my most forceful team talk yet; I had to get a performance out of them second half because first half we didn't turn up at all.
"I'm so pleased with the reaction that we got second half, and I'm so pleased for Jo Kuffour getting a goal. Second half we did it right and we rightfully got the three points.
"I have standards and they have to be met. I'm pleased with the result and at last we've got a free week, because a few of the boys are dead on their feet.
"Age means nothing to me because I know ability and form at the moment is important.
"If Kortney (Hause) keeps performing the way he has, he'll keep playing. And I'm sure he has got a big future because he's looking very assured."