[richchurcher]

As furgooswft13 notes, you can use

  Ctrl-O <command>

to issue single normal mode commands from insert mode. Most purists would say switch to normal mode to navigate, and by and large that's true (especially, IMHO, if you bind 'jk' to Esc which is much faster for a touch typist). However, insert mode does let you do this to avoid the arrow keys:

  inoremap <A-h> <Left>
  inoremap <A-l> <Right>
  inoremap <A-k> <Up>
  inoremap <A-j> <Down>

Which some would say enforces 'bad' habits, but I reckon do whatever feels effective to you. If you do find yourself leaning on the direction keys for more than a few repeats, there's probably a faster way though!