Warrington Wolves' Evans and Flower of Wigan Warriors will be in action in Saturday's Grand Final at Old Trafford.
Both players had been named in an initial 29-man training squad, but have made themselves unavailable due to club commitments.
Wales will also be without Tyson Frizell, who has been included in Australia's Four Nations squad.
Salford Red Devils' Craig Kopczak will captain a squad featuring the majority of last year's European Championships winning side.
Wales host Serbia at Stebonheath Park's Llanelli on 15 October and and face Italy in Monza on 29 October.
"It is an important period for Wales as we aim to make the World Cup next season," head coach John Kear said.
"Our group of players is a very hard working one and there is always a good atmosphere in camp, so we are looking forward to getting back to work."
Kear has said he would be happy for second row Frizell to represent Wales once again in the future.
Frizell, capped five times by Wales, has been included in Australia's squad for the Four Nations.
Australian-born Frizell qualifies to play for Wales through his Swansea-born father and can switch to the Kangaroos as they are a tier one nation.
"There's no hard feelings," Kear told BBC Wales Sport.
"Should ever the opportunity arise in the future for him to switch allegiance back to Wales then we'd be more than happy to welcome him back."
Wales squad: Elliot Kear (London Broncos), Rhys Williams (London Broncos), Calvin Wellington(St Helens), Christiaan Roets (South Wales Ironmen), Regan Grace (St Helens), Courtney Davies (South Wales Ironmen), Ollie Olds (Souths Logan Magpies), Gil Dudson (Widnes Vikings), Lloyd White (Widnes Vikings), Craig Kopczak (Salford Red Devils - captain), Rhodri Lloyd (Swinton Lions), Lewis Reece (Gloucestershire All Golds), Phil Joseph (Salford Red Devils), Steve Parry (Gloucestershire All Golds), Joe Burke (Oldham Roughyeds), Jake Emmitt (Swinton Lions), Anthony Walker (Wakefield Trinity Wildcats), Andrew Gay (Mackay Cutters), Matty Fozard (Sheffield Eagles), Morgan Evans (Gloucestershire All Golds), Ian Newbury (South Wales Ironmen), Connor Farrer (South Wales Ironmen)
Super League players Rhys Evans and Ben Flower will be unavailable for Wales' 2017 Rugby League World Cup Qualifiers.