Carl, it's more complicated than that.

When you CLOSE the contacts, to turn the a pump motor ON, you can have a high current inrush that is sometimes a full multiple of the maximum running amps. But what tends to kill timers and relays is the induced current overload that results when you OPEN the contacts, to turn the pump OFF. This results in the timer (or relay) having to BREAK a much larger current than the maximum current the circuit carries.

This is the reason a relay that is rated for a 30A resistive load may only be rated for 1HP 110V motor load -- that is nominally about 8 or 9 amps. If you try to use a 10A resistive relay for a 1HP 110v motor load, you'll tend to burn out the contacts very quickly.