Is there a way of rebinding keys only in Insert mode ?

[roomtin]

In my normal vimrc I like to bind "fj" to in insert mode with inoremap fj <ESC> because I find it easier than reaching up to hit the escape key and "fj" is a very uncommon character pair in English. However using this in the plugin results in it informing me that inoremap fj <ESC> is not an editor command. Is there a different way to accomplish this in the plugin ? Thanks.

[roomtin]

After some more tinkering I've gotten this to work correctly so I'll leave an answer for others who come across this.

The correct way to remap escape the way I wanted to is to use the following: imap fj <Esc>