Everything wears out of course, but I've had mine for 7 years going back and forth to work every day and never replaced my breaks or chain or cassette. Maybe you experience a quality issue if it's a frequent issue?
If the motor is in the hub, then I can believe wear on the chain and cassette is minimal. And if you use brakes very sparingly, they could also last for a long time. I'm interested in the brand of your pads, I need those! I have to change mine every 1000 kilometres.
