Nanostructured and conventional WC-Co coatings were deposited on 1Cr18Ni9Ti stainless steel substrate using an atmospheric plasma spraying facility. The friction and wear behavior of the resulting cermet composite coatings in water environment was comparatively investigated. It was found that the nanostructured and conventional WC-Co coatings had similar friction coefficients under the same testing conditions. However, the nanostructured WC-Co coating had better wear resistance than the conventional WC-Co coating as slid against both Si3N4 ball and stainless steel ball. At the same time, the stainless steel or Si3N4 counterpart matched with the nanostructured WC-Co coating had a much smaller wear rate as well, and as compared to rubbing against the ceramic ball counterpart, the two types of coatings rubbing against the stainless steel ball registered lower friction coefficients and wear rates.