Cavitation Pump

I've long wanted to build one of these things and connect it to a stationary bike, just to see if it's possible to heat water effectively. I reckon you could spin one of these things at 2000 - 2500rpm without too much hassle. It's be nice if you could, say, produce a nice warm (read steaming) bath of water in half an hour's work (using an external low pressure, low power pump of course. Not having any experience with pump seals, I'd be much obliged if anyone would be interested in having a look at this and tell me how to seal it properly. It doesn't need to be capable of more than a couple hundred millibar, tops. Although if it could cope with mains pressure, up to 10ish bar, that'd be ideal...