Grooves of 1 mm depth and of different widths 1, 1.5, or 2 mm are made on the surface of AA5083 Al alloy plates and filled with 1.07:112.35 μm alumina powder. Then, the surface is treated with friction stir processing “FSP" to form a composite surface layer of AA5083 matrix reinforced with alumina particles. FSP is carried out using a tool rotational speed of 1400 rpm, processing speed of 25 mm/min and a plunge depth of 4.3 mm. Prepared surface composites are subjected to microstructure investigation, Vickers hardness measurements, and wear rate determination. For comparison, as-received and FSP 5083 Al alloy are subjected, also, to similar tests. The composite layer thickness decreases from 0.8 to 0.7 and to 0.6 mm at 1, 1.5, and 2 mm groove widths, respectively. It seems that, the stirring conditions i.e. 1400 rpm rotation speed, 25 mm/min travel speed and 4.3mm plunge depth are not suitable to specimens with alumina grooves wider than 1mm, where the alumina powder is expelled out of the stir zone, as indicated by micro-structural observations. The surface micro-structure of 1mm alumina groove specimens shows highest alumina volume fraction. Such specimens possess highest surface micro-hardness numbers of about 120, while those with wider grooves possessed values of only about 100. Moreover, FSP of the surface layer increases the wear resistance of present alloy, especially at higher sliding velocities. However, the wear resistance is dramatically raised when alumina powder is added to form surface composite.