Wear in rugs can look similar to corrosion in some ways. That said, there are a few things that distinguish it from oxidation. A rug wears simply as a result of people walking on it over time. Wear reflects the utilitarian purpose of the rug.
As people walk on the rug over long periods of time, little pieces of the wool break off. Eventually, just as with corrosion, the white warp will begin to show through. This might appear as little white flecks, singular white knots, or it might be more pronounced, and you can see white warp threads on the front (pile side) of the rug. On many rugs with heavy wear on the pile, the fringe or the ends will tend to be ragged or very short, too.