England Under-20 cap Everard completes a move from Leicester after impressing in the friendly win over Munster, while former Newport Gwent Dragon and Wales Sevens international Harris comes in after playing for Blackheath last season.
Director of rugby Dai Young has also handed a trial to Argentina international Genaro Fessia, who missed out on his country's World Cup squad, as the London club look for strength in depth following the news that Tom Rees will be out for six to nine months with a knee injury.
Young said in a Wasps statement: "Back row is an area we needed to strengthen as we've had some injuries there which means we are lighter there than we'd like.
"We've brought in two young flankers who have plenty of potential and Genaro's international experience will certainly help provide much stronger depth to our back row."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.