Industrial wear indicators comprised of layers of ablative materials; Industrial wear inserts comprised of layers of ablative materials; Replaceable industrial wear indicators for industrial equipment and apparatus; Replaceable wear indicators insertable into sacrificial machine parts; Replaceable wear indicators insertable into mining haul truck bodies and trays; Industrial wear indicators comprised or layers of materials having different reflectances; Industrial wear indicators comprised of differently-coloured layers of materials; Industrial wear indicators comprised of threaded inserts; Industrial wear indicators comprised of friction-fit inserts; Replaceable sacrificial industrial wear indicators; Replaceable sacrificial industrial wear inserts