The invention relates to a powder composition used for the fabrication of casting inserts designed to produce local composite zones resistant to abrasive wear, wherein said composite zones are reinforced with carbides and borides or with mixtures thereof formed in situ in castings, and wherein said powder composition is characterized in that it comprises powder reactants of the formation of carbides and/or borides selected from the group of TiC, WC, ZrC, NbC, TaC, TiB2, ZrB2, or mixtures thereof, said carbides and/or borides forming after crystallization particles reinforcing the composite zones in castings, and wherein said powder composition further comprises moderator powders in the form of a mixture of metal powders, which after crystallization form matrix of the composite zone in casting. The invention also relates to a casting insert for the fabrication in casting of local composite zones resistant to abrasive wear, and to a method for the fabrication of local composite zones in castings, using for this
