you can investigate a developpement of an a polymer in situ on the metal surface

What technique do you suggest?

This depends on your wear conditions! 

When hard coatings such as TiN are applied on the SS substrate, due to the presence of coating defects, SS substrate can be severely corroded if the corrosive medium contains halide ions.  So be cautious to use this approach.

Heat treatment, coating with a hard material, surface alloying with melting the surface and supply external alloying material by using process like laser. but SS have a different grades, according to the type of stainless steel appropriate process should be selected. 

Another possible way is to using nitriding process to form a hard nitride layer.