The two teams met again at Adams Park after their first League Two meeting on August 25 was called off due to heavy rain with Bristol Rovers 3-1 up.
But the visitors were always up against it this time around as Joel Grant put the home side ahead after 11 minutes, and Ainsworth came on at half-time to head home his side's second, extending their unbeaten run to three games.
Wycombe took the lead when Grant ran at the Rovers defence and fired past Sam Walker from the edge of the area.
Dean Morgan nearly doubled Wycombe's lead before Bristol Rovers should have equalised on the half hour mark but David Clarkson could only head a Michael Smith cross over the bar.
Ainsworth doubled his side's advantage on 55 minutes with a diving header before Rovers' defeat was compounded when Matt Lund was sent off in injury time for a frustrated lunge.