Impact wear is the striking or slamming contact of one object against another. a battering, pounding type of wear that breaks, splits, and deforms metal surfaces.

Abrasion is the wearing of surfaces by rubbing, grinding, or other types of friction. It usually occurs due to metal-to metal contact. It is a scraping, grinding wear that rubs away metal surfaces and can be caused by the scouring action of sand, gravel, slag, earth, and other gritty material.

Erosion is the wearing away or destruction of metals and other materials by the abrasive action of water, steam, slurries which carry abrasive materials. Pump parts are subject to this type of wear.

Compression is a deformation type of wear caused by heavy static loads or by slowly increasing pressure on metal surfaces. Compression wear causes metal to move and lose dimensional accuracy.

Cavitation wear results from turbulent flow of liquids, that carry small suspended abrasive particles.

Metal-to-metal wear is a seizing and/or galling type of wear that rips and tears out portions of metal surfaces. It is often caused by metal parts seizing together because of lack of lubrication. It usually occurs when the metals moving together are of the same hardness. Frictional heat promotes this type of wear.

Corrosion wear is the gradual deterioration of unprotected metal surfaces, caused by the effects of the atmosphere, acids, gases, alkalies, etc. This type of wear creates pits and perforations and may eventually dissolve metal parts.

Oxidation is a type of wear causing flaking or crumbling layers of metal surfaces when unprotected metal is exposed to a combination of heat, air and moisture. Rust is an example of oxidation.