Hey, you're a submariner. Just call up the guys at GE Electric Boat. They figured that problem out for subs. Of course it may cost you a few billion for the solution.

Seriously though, that's a problem a lot of folks have had with bigger pumps. I think the solution has been to pinch back on the flow from the pump or eventually downsize the pump. Bt pinching back the flow, you increase the pressure on the pump head, causing the bubbles to collapse. Of course, back pressure is not necessarily good, in the long run, for the pump.