Lealiifano's battle with leukaemia and Matt Toomua's departure to Europe left the Brumbies scrambling for options at the end of last season.
A fruitless search at home prompted Larkham to look across the ditch, where he said there were "four or five" others he could have picked from before settling on Hawera, who came through the Waikato system but played last year for Southland.
"There's a bit of a lack of Super Rugby-ready players in Australia - there's a good crop of players coming through in the inside backs positions, but are they ready for Super Rugby? We weren't really sure," Larkham told AAP.
"There probably is a little bit more depth over there and they're not getting the opportunity some of the others have been given.
"It makes sense for us to make sure we're not closed down with our blinkers on and just looking locally or nationally.
"We do have to look overseas at times and the beauty of Wharenui is we can develop him up and he might be an asset for Australia in years to come."
Hawera is set to start at No.10 in next weekend's season-opener against the Crusaders in Christchurch.
Larkham confirmed he'll be part of a raw playmaking axis alongside young halfback Joe Powell and recruit Kyle Godwin, who will start at inside centre.
Larkham is confident Hawera will make an immediate impact.
"The one thing noticeable with Wharenui when I came back from my break pre- Christmas was that his communication was just at a different level to everyone else," he said.
"Even to the guys who have been here in the past, you can see he's clearly played at that higher level - not just club rugby but the ITM Cup level before.
"The way he demanded authority out on the field and the way he communicated with the players was top-notch.
"He's a natural New Zealand player who sees the space quite well.
"He's very good at all the unstructured stuff, but we've given him a little bit of structure now and he's revelling in that at the moment.
- NZ Herald and AAP
