A mechanical fastener assembly for securing first and second workpieces (10,12) having aligned bores (18a, 18b,24a,24b), the mechanical fastener assembly comprising: a mechanical fastener having a shaft configured to be at least partially received within the aligned bores of the first and second workpieces; and a slotted insert (402,412,414) surrounding at least a portion of the shaft of the mechanical fastener and comprising a head portion (406,432) and an associated body portion (404,416); the body portion (404,416) being configured to be at least partially received within the aligned bores of the first and second workpieces, the end of the body portion away from the head portion being a free end or lead-in end, and at least one slot extending from said free end or lead-in end along only a portion of the length of the body portion, and the head portion being an enlarged head portion (406,432) having a larger diameter than the body portion and configured to be positioned outside the aligned bores of the first and second workpieces, wherein an inner surface (424,436,438) of the slotted insert (402,412,414) is configured to surround at least a portion of the shaft of the mechanical fastener, and an outer surface of the body portion (404,416) of the slotted insert is configured to engage at least a portion of the aligned bores of the first and second workpieces, the outer surface being tapered such that at the free end or lead-in end it has a smaller outer diameter than at the end of the body portion directly adjacent to the head portion (406,432), wherein the slotted insert (402,412,414) is formed of a metal material. a mechanical fastener having a shaft configured to be at least partially received within the aligned bores of the first and second workpieces; and a slotted insert (402,412,414) surrounding at least a portion of the shaft of the mechanical fastener and comprising a head portion (406,432) and an associated body portion (404,416); the body portion (404,416) being configured to be at least partially received within the aligned bores of the first and second workpieces, the end of the body portion away from the head portion being a free end or lead-in end, and at least one slot extending from said free end or lead-in end along only a portion of the length of the body portion, and the head portion being an enlarged head portion (406,432) having a larger diameter than the body portion and configured to be positioned outside the aligned bores of the first and second workpieces, the body portion (404,416) being configured to be at least partially received within the aligned bores of the first and second workpieces, the end of the body portion away from the head portion being a free end or lead-in end, and at least one slot extending from said free end or lead-in end along only a portion of the length of the body portion, and the head portion being an enlarged head portion (406,432) having a larger diameter than the body portion and configured to be positioned outside the aligned bores of the first and second workpieces, wherein an inner surface (424,436,438) of the slotted insert (402,412,414) is configured to surround at least a portion of the shaft of the mechanical fastener, and an outer surface of the body portion (404,416) of the slotted insert is configured to engage at least a portion of the aligned bores of the first and second workpieces, the outer surface being tapered such that at the free end or lead-in end it has a smaller outer diameter than at the end of the body portion directly adjacent to the head portion (406,432), wherein the slotted insert (402,412,414) is formed of a metal material.