The biggest cause of pump failure is the pump getting clogged and dirty. At least once monthly uplug it, remove the tubing that goes out of it. Get the garden hose with a strong nozzle on it. Turn it on full blast and put it in the hole where the water comes out. You will blow the debris out of the pump and impeller. The impeller needs to turn freely. Test it with a screwdriver.
Do not pull your pump out of the water using the cord as a handle. That is the second largest cause of pump failure.
One of the first signs a pump is failing is it begins to run intermittently. There is a safety mechanism in the pump that turns it off when it gets too hot. If that happens, start shopping because your pump is not long for this world.
I love Oase pumps, so check them out. They have a great warranty and cost very little to operate.