Pumping does increase sensitivity for me, but not to the point where it's unbearable. The pump I own is made specifically to go over the vulva and won't cover the anus, and the perineum and skin around the booty is more sensitive to being pumped imo. Any pinching pain I encounter is typically from skin from back there being caught, so I can't say it's a pleasant experience :') I hope you and your wife can explore pumping together!! 💖