Being that the vehicle ran prior to the repair, my first thought would still be to double and triple check everything that was done involving the water pump replacement.
Check for any damaged wiring or broken connectors.
If you have gone in and replaced any timing components, I would verify that all the timing marks align correctly and that #1 cylinder is at TDC.
If all else fails, start with the basics.
Fuel
Air
Spark
Compression.