FamousDan -- I can hear the knocking sound at the water pump with a stethoscope but I can also hear it almost just as well to the right on the drivers side of the block. The sound seems to radiate. I can even hear it in the EGR valve, though not quite as strong. How long did your water pump last before it failed? I have had this sound for months and still drive the car every week.It's probably not the case here, but the water pump in my AWM made sounds similar to that as it was going out.
I know you changed it just a few miles ago, but try your stethoscope screwdriver closer to the water pump just in case.