Rear wheel bearings keep going after only a short period of use.

You have to jack the vehicle off the ground, then grab each tire at the 12:00 and 6:00 positions. Then as hard as you can try to wiggle the tire up and down. If there is any movement then that wheel bearing needs to be replaced.

Bearings should more than likely should have been REPACKED at 50,000km service. Sounds more like a lack of service problem than a manufacturers problem

It's not the wheel bearing, it's the sensor or the wiring. You can get wiring and connectors from ANY GM dealer.

If you're talking about the front wheel bearings, they can't be serviced. They can only be replaced. They are sealed for life (even if the life seems to be a little short).
Here's the front bearing:


I never replaced the rear bearings on my 2002 Escape 4X4, but here's a picture of the rear hub.

If it was me i would replace the whole thing. You have to ask yourself how long you are going to keep this vehicle. If for a short time, only the bearing. If you will keep it for a longer period of time i would replace the whole thing, while you have it apart.

it could possibly be the bearings are shot

It sounds like one of your wheel bearing needs to be replace, most likely one of the rear bearing may have gone dry and needs to be replaced soon as possible before you have a total bearing failure and loose a wheel. With the car parked, go to each wheel and push back and forth on the top (side to side) you should be able to hear and feel which wheel has the play since it's will feel and sound different from the other wheels. The rear wheel bearing can be replaced with simple tool and under 1 hour if your good with tools and the front will have to be brought to a shop since your going to need am impact gun to remove the front axle nut from the wheel hub. Good luck and hope this helps. Keep me posted if your going to replace the rear wheel hub your self and i can give you the instructions to replacing the hub. I believe the rear hubs goes for around $170.00 at Auto Zone and they can give you the step by step instructions too. 

the reason is that you a disallighned rear wheel try to check them if their allighned.

It's the wheel bearing. Guaranteed. Just replaced mine. Go to Audiworld tech articles for step by step instructions on how to test the wheel bearings. They must have been put in wrong last time or they just went out again.

Ouch, get your wheel bearings checked. I had a 97 Hyundai and in the 3 years I had it, the front bearings had to be replaced twice and the rear once once.