Around 30 Unite members, in coordination with RMT members also taking industrial action, will strike from Monday, June 28, to Sunday, July 4, with an overtime ban on Monday, July 5.
Stadler said it has plans which mean there will be no impact on the service.
In October 2020, Stadler won a £300 million contract to build 42 new trains, rebuild the Gosforth depot and maintain the Nexus stock for 35 years.
Unite says the company has initiated the freeze despite recording an 8% increase in net profits during 2020, while its annual report said the division responsible for its Tyne and Wear operations brought in a “record 1.46 billion Swiss francs (£1.2 billion) in 2020”.
Unite regional coordinating officer Suzanne Reid urged the company to return to the negotiating table and said: “The responsibility for these strikes, which will cause Metro misery for the travelling public during the height of the summer, sits squarely with Stadler.
“Stadler is in excellent financial health and has benefited from the hard work of our members who maintained the Metro stock 24/7 right through the pandemic.
“The very least they deserve is a reasonable pay rise, but instead Stadler has chosen to hoard its considerable profits and freeze their wages.”
A spokesperson Nexus: “We are encouraging both sides in this dispute to seek a resolution as soon as possible.
"The last thing Metro and its customers need is industrial action as we start to recover from the impact of the pandemic.”
A statement from Stadler added it was keen to reward staff and has reviewed benefits, but said employees would not be getting a rise due to the impact of the pandemic.
It said the action was disappointing, adding: "We are keen to see this dispute resolved and have stressed to the unions that we are always open to discussions with them, so that a solution can be found quickly for the benefit of our staff and the passengers we serve.”