This is the throat block for direct drive extrusion, Anet8 is a cheap clone of Prusa printers, so it's easy to find parts for Anet printers.
This is one extruder kit that may help your needs, 1 Unidades Impresora 3D makerbot MK8 Extrusora De extrusión de Aluminio Bloque de DIY Kit para Reprap i3. This is a link for Aliexpress - of course there are other dealers.
This is part of filament drive. Anets do not sell it separately, only as a part of extruder assembly, but other manufacturers may make incompatible parts: of different size (not fitting into bracket), filament channel position, etc.
Like @ZuOverture said the name of this component is the filament drive. Most of the manufactures sell the whole extrusion device already assembled, to avoid mismatches between the components of the extrusion device. If your device is somehow damaged, and without possibilities to be used in the printer the easiest solution would be to buy a new extrusion device. If financially is unfeasible for you, you may have the option to generate the 3D model of this piece and share the file to someone who could print this component for you.