A good quality pool pump should be expected to last many years of useful service if it is properly maintained. The pool needs to be kept within the proper ranges of pH, acidity and alkalinity, as well as being sure to never over stress the pump.
An average life of a pool pump is about 10 years. The better you care for your pump the longer they will last. Be sure to keep the air vents free from things like dirt, leaves or hair.
You can expect a standard pool pump motor, used for recirculation and pushing the pool water through a filter to last at least five seasons under normal conditions.