Select com passagem de parâmetros

const text = 'INSERT INTO users(name, email) VALUES($1, $2) RETURNING *'
const values = ['brianc', 'brian.m.carlson@gmail.com']
 
// callback
client.query(text, values, (err, res) => {
  if (err) {
    console.log(err.stack)
  } else {
    console.log(res.rows[0])
    // { name: 'brianc', email: 'brian.m.carlson@gmail.com' }
  }
})
 
// promise
client
  .query(text, values)
  .then(res => {
    console.log(res.rows[0])
    // { name: 'brianc', email: 'brian.m.carlson@gmail.com' }
  })
  .catch(e => console.error(e.stack))
 
// async/await
try {
  const res = await client.query(text, values)
  console.log(res.rows[0])
  // { name: 'brianc', email: 'brian.m.carlson@gmail.com' }
} catch (err) {
  console.log(err.stack)
}

Select

// callback
client.query('SELECT NOW() as now', (err, res) => {
  if (err) {
    console.log(err.stack)
  } else {
    console.log(res.rows[0])
  }
})
 
// promise
client
  .query('SELECT NOW() as now')
  .then(res => console.log(res.rows[0]))
  .catch(e => console.error(e.stack))

Insert

const query = {
  text: 'INSERT INTO users(name, email) VALUES($1, $2)',
  values: ['brianc', 'brian.m.carlson@gmail.com'],
}
 
// callback
client.query(query, (err, res) => {
  if (err) {
    console.log(err.stack)
  } else {
    console.log(res.rows[0])
  }
})
 
// promise
client
  .query(query)
  .then(res => console.log(res.rows[0]))
  .catch(e => console.error(e.stack))

Reference: https://node-postgres.com/features/queries