it is actually very simple to rebuild, especially since you can pull the pump off in about 10 minutes and bring home to rebuild. I forget how much the seals and bearings were but I used Torresen for the parts. I ended up stripping and painting the pump / pulley while I was at it.
Marine Diesel Engines and Engine Parts from Torresen Marine's Marine Diesel Direct - Universal - Volvo - Westerbeke - Yanmar - MASE
I actually keep a spare pump on board, so I put in the spare, and rebuilt the leaking one for the new spare. (mechanical engineer so I am a little excessive compulsive)