Did you take it back apart to inspect the impeller? I can't imagine you had a faulty impeller that sheared all the vanes immediately. Did you bend the vanes the right way when installing? Did you take the raw water pump off to do the job? If so, maybe the notch in the shaft didn't go all the way back into that plastic thing (companion flange?) between the pump and the fuel injector pump? Did you remove the cam (bronze wedge half-moon thing inside pump held in by one screw) that caused the vanes to compress on one side?
Those are the only things I can think of.
Glenn (Wizard)
"The Reel One"
26' Billfisher