how can i check water pump to make sure it's ok

removed and gutted old stat and reinstalled but left radiator hose off stat housing but still connected to top of radiator. duck taped a garden hose into loose hose and turned water on.
water flew through radiator, water pump, and engine and out of the stat housing. it appears there's no blockages. next i disconnected the hose at bottom of radiator and stuck the loose end in a container of water with the garden hose in it and ON (to keep it full) and the other end of the radiator hose still connected to the water pump.  i  then started engine to see if water pump would pull the water out of the container and pump it through the engine but it
didn't pump a drop. i checked and made sure the radiator hose in the container was free and able to suck water . what am i missing here?   the water pump didn't make noise or wobble but i removed it anyway and on a mighty max that's no fun. it looks like a 3 year old water pump alright but there's no shaft play or stoppage and the impeller turns with the shaft. yes,
the engine still overheated after i gutted the stat which left about a one inch diameter opening.
Anyone got a thought about this?  It's been a pain. sorry about the drawn-out story. richard