Wear and friction are major issues in using aluminum alloys and are often avoided through using dissimilar materials as coatings or overlays.  Aluminum matrix composites offer improved tribological properties but with lower mechanical properties, higher costs, and difficult fabrication issues.  In-situ composite surfaces have been created by adding particles to existing surfaces of fabricated parts through friction stirring.  The composite layer can be several millimeters thick.  The underlying material retains its properties as only the surface is modified.  Various types of particles can be added to the surface of aluminum parts at volume fractions of 30%, with higher amounts possible, through friction stirring.  The hard particles add wear resistance to the surface while dry lubricants reduce friction.  Mixtures of these additives can provide tailored friction and wear response.  Additions are integral parts of the surface leading to excellent adhesion.  Examples will be shown of Mo2S and SiC additions to wrought aluminum.  Mechanical properties, tribological properties and microstructure will be presented.  These composites can also be created in cast or powder metallurgy parts.  The application of this technology in Aerospace will be discussed.