Insert: -i [dest] [cnt] ...
Inserts bytes in the file at the destination, repeating the bytes for a number of times.
hexed -i 100 10 01 02 03 file
This will insert the bytes 0x01 0x02 0x03 at 0x100 for 0x10 (16) times. For an empty value this command will insert 0 for count times.