I have a '00 cavalier with the LD9, and have had it since it was new. It now has 127K and counting. Two years ago I was told my water pump was leaking, but it has not failed yet. I did change the coolant at 100K. I used to frequent www.j-body.org and it seemed like this was a common topic. A lot of the members there said this was an issue and happens to most of these engines. Hopefully you have a good pump in now, as the $800 repair is way too much to do more than once or twice. Good luck.
btw, the engine code is LD9 and not LH9.