Regarding the relay, it's nearly impossible to say if the 4 pole you bought will work. Though very similar in layout/design, there are quite a few possible combinations for them? The fact it "started" to work would make me thing it's ok, but that's no guarantee.
Don't forget that for the motor to work it needs power AND a good ground?
What's going on could be checked by checking for voltage at the pump motor while somebody holds the switch. If you have voltage, the relay is likely OK and there's an issue with the pump motor (usually repairable). If you do not have voltage, the problem may lie with the realy - or the switch that supposed to be turning the relay on.
1997 37' HR Endeavor, 275hp Cat, Freightliner
03 CR-V Blue Ox, Ready Brake