The phrase "erode the quality" is correct and usable in written English.
You can use it to describe a gradual decrease in the level of quality of something over time. For example, "Continual budget cuts have eroded the quality of education in our local school district."
The attacks leave foreign advisers weary and erode the quality of training.
The National Union of Students (NUS said the move would erode the quality of a university education.
This pattern of development has the potential to erode the quality of the lowland habitats most used by park wildlife.
Many administrators fear such departures could erode the quality of government-sponsored technical and scientific research over the next several years, including some work affecting national security.
While coups d'état, revolutions and civil wars still occasionally bring down established democracies, it's more common for democratically elected leaders to gradually erode the quality of democratic institutions.
It essentially achieves the North Korean and Chinese goal of limiting American military freedom of action in the Pacific, and over time it would erode the quality of the American-South Korean military deterrent.
Many parents worried that the Latino influx strained schools' resources, eroding the quality of their children's education.
"Vacancies cannot remain at such high levels indefinitely without eroding the quality of justice," the Chief Justice said.
Mr. McCall said the lack of professional educators on the boards had eroded the quality of the colleges and limited academic freedom, while tuition rose faster than in other states.
But further cutbacks in Legal Aid's jurisdiction and income would impair its ability to hire new lawyers and to provide investigators and other central support services, inevitably eroding the quality of representation afforded poor people.
