I see this question fairly frequently on various forums, asking for just about every RC out there. Bottom line is that for 1/10 scale there is no need for a metal spur and if you did use one, anything that would damage the spur would instead damage a more critical part that would be harder and more expensive to replace.
If you're going through a lot of spur gears it's almost certainly one of these things:
- Gear mesh. A common culprit here is motor mount screws that don't hold, so you might set your mesh well and have the motor slip on a hard landing.
- Inproper slipper settings. The idea of the slipper is to break loose momentarily if you have a sudden jolt on the drivetrain. Usually that comes from landing while hard on the throttle.
- Bad or dirty pinion. Some pinions are made of softer metal and the teeth will bend, chip, or become curved. Check that the pinion is clear of dirt and small rocks and that the teeth are still in proper shape.