All pen tablets (those without a screen) will experience some form of wear. The amount and type of wear will be affected by:
The material of the surface
The texture of the surface
The material of the nib
How you draw
Other sources of damage not related to normal use of the pen tablet
In general, surface wear is not a problem, unless it interferes with your pen. Typically this means a deep scratch which deflects the tip of the pen. This deflection may be strong enough that you will get little "bumps" if you try to draw a line across the scratch.
Texture erosion - where the surface texture starts getting a little smoother as you continue to move your pen over it. More here: Texture erosion on pen tablets.
False scratches - False scratches are things that look like scratches but are really the result of a tablet surface that isn't clean. More here: False scratches
Scratches - permanent grooves cut into the surface. More here: Scratches on pen tablets.
There are options to help protect the surface
Maintain your pen nibs so that they don't develop a flat edge
Use a felt nib which is softer than a plastic nib.
Don't press down so hard on the tablet
When traveling with the tablet, make sure you put it inside something to prevent something from scratching the surface