A unique iron base alloy for wear resistant applications, characterized in one aspect by its hardening ability when exposed to a certain temperature range, is useful for valve seat insert applications. The alloy also possesses excellent wear resistance, hot hardness and oxidation resistance. The alloy comprises less than 0.1 wt % carbon; about 18 to about 32 wt % molybdenum, about 6 to about 15 wt % chromium, about 1.5 to about 3% silicon, about 8 to about 15 wt % cobalt and at least 40% iron, with less than 0.5 wt % nickel. In another aspect, for lower temperature applications, the cobalt is optional, the nickel content can be up to 14 wt %, but the molybdenum must be in the range of about 29% to about 36%. In one further aspect, for higher temperature applications, the cobalt is optional, but may be used up to 15 wt %, nickel must be used at a level of between about 3 and about 14 wt %, and the molybdenum will be in the range of about 26 to about 36 wt %.